For many years, automobiles have been provided with occupant restraint devices for protecting vehicle passengers from injury due to sudden changes in vehicular velocity as would result from an impact or sudden braking. Lap belts in automobiles have been supplanted by three point occupant restraint systems intended to add still greater injury protection. Even greater safety has been realized by the additional provision of cushioning air bags that explode into a nearly enveloping protective position in the event of an automobile collision.
Most notably, however, large transportation vehicles have historically been left completely without occupant restraint mechanisms. For example, seat belts traditionally have been foregone in school buses because the safety mechanisms were considered unduly expensive and unnecessary in light of the general infrequency of accidents and the typically minor injuries resulting therefrom. Also, later model buses provide alternative safety mechanisms designed to absorb passenger impact in the event of an accident or the like.
Termed compartmentalization, this method contemplates having the school bus occupant thrown into the seat forward of the occupant's seat. Each of the seats on such school buses are designed to absorb and dissipate the kinetic energy of the thrown rider. To do so, compartmentalization-type seats are padded sufficiently to absorb energy from the thrown occupant's head, torso, and knees such that energy is distributed over these three typical impact points. Furthermore, the seats are manufactured to particular dimensional specifications and are set at particular distances. Fortunately, compartmentalization has been found to improve overall occupant safety, which has led to a reduction in serious injuries.
Unfortunately, compartmentalized buses continue to leave their completely unrestrained occupants vulnerable in a number of ways. For example, in a side impact, occupants often are hurled into bus windows or walls or into the edge of an adjacent seat. Most tragically, unrestrained occupants have been ejected from within buses only to find themselves thrown into the path of oncoming traffic, placed at risk of having the vehicle roll over and crush them, or placed in similar life threatening situations. Further still, impacts while an individual is in a bent-over position can lead to a head-first impact with a seat back, which could result in spinal and head injuries.
Advantageously, occupant restraint systems in the form of two-point restraints, or lap belts, have been provided, and these systems serve to prevent an occupant from being ejected from the bus seat by securing the occupant's lower body to the seat bottom. Disadvantageously, lap belts fail to restrain the occupant's upper torso and head such that these body parts will tend to experience a potentially violent, whipping movement in an impact situation. This movement can lead to head, neck, and spine injury as the occupant may be simply thrashed about or snapped into the forward bus seat or the wall of the bus.
In light of the above, it becomes clear that providing an effective occupant restraint system that restrains both the upper and lower portions of an occupant's torso against both forward and lateral movement would greatly increase the safety of school bus occupants. The unfortunate reality, however, is that there are so many buses in service today that retrofitting them all with a truly effective occupant restraint system that resists tampering and inadvertent disablement would be unrealistic unless the occupant restraint mechanism were capable of being attached to a bus seat in a time and cost-effective manner.